Uside down plants
Part of a show this summer at the local art gallery was upside down plants of all types, tomatoes cucumbers, house plants you name it. They were planted in detergent bottles and other large plastic bottles, with the plant coming out of the spout and the bottoms cut out for dirt and watering.
they were hung so the opening or spout hole was on the bottom and the plant was growing out of it. I'm not sure how well they produced, but it was a fun recycling project. I might try a few next year.